It is common knowledge that oil and gas deposits in the earth's crust are recovered by drilling holes down to the deposit, to allow oil and gas deposits to be drained to the surface.
The equipment used to drill holes in the earth's crust primarily comprises a drilling derrick formed as a trussed steel structure. In the drilling derrick there is a wireline based drawworks for hoisting and deploying drill pipes. A great deal of auxiliary equipment is also used to handle drill pipes and to set casing in the borehole.
Floating or fixed platforms provided with the required drilling equipment are utilized to recover oil and gas deposits from great depths. These types of platforms are large and expensive structures, as the drilling equipment is large and heavy. In addition to the actual drilling equipment, marine risers must also be used to circulate drilling mud between the platform and the seabed during the drilling operation. Floating platforms also require heave compensation to accommodate wave motion against the platform relative to the seabed.
As an alternative to drilling from floating drilling platforms, the drilling rig may be arranged directly on the seabed, obviating the need for large and expensive platforms.
Today, the oil industry possesses a great deal of advanced equipment developed for remote-controlled subsea operations. This is technology that is available and may be used during a remote-controlled drilling operation where the drilling equipment is situated directly on the seabed.
Furthermore, it is necessary to meet the relatively strict requirements set by the authorities in connection with environmental pollution and the target of zero discharge to the environment.
Prior art does not provide a solution to these problems in connection with drilling rigs situated on the seabed.